Comparative effects of unilateral and bilateral subthalamic nucleus deep brain stimulation.

OBJECTIVE: To compare the effects of unilateral subthalamic nucleus (STN) deep brain stimulation (DBS) with bilateral STN DBS in advanced PD. METHODS: Our initial 10 consecutive patients with medication-refractory motor fluctuations and levodopa-induced dyskinesias undergoing chronic bilateral STN DBS underwent a standardized evaluation of unilateral and bilateral STN DBS in the medication-off state 6 to 18 months after electrode implantation. RESULTS: Bilateral STN DBS improved the mean total Unified Parkinson's Disease Rating Scale motor score by 54%, whereas unilateral stimulation improved motor scores only 23%. Unilateral STN DBS improved postural stability and gait 14%, other axial motor features 19%, and overall parkinsonism in limbs contralateral to stimulation by 46%, including an 86% improvement in contralateral tremor. However, bilateral STN DBS resulted in greater improvement in each of these domains, including limb function, i.e., the reduction in scores from the limbs on one side was greater with bilateral than with unilateral stimulation of the contralateral STN. CONCLUSIONS: Bilateral STN DBS improves parkinsonism considerably more than unilateral STN DBS; bilateral simultaneous electrode implantation may be the most appropriate surgical option for patients with significant bilateral disability. Unilateral STN DBS results in moderate improvement in all aspects of off-period parkinsonism and improves tremor as much as is typically reported with DBS of the ventral intermedius nucleus of the thalamus (Vim). For this reason, STN DBS may be a more appropriate choice than Vim DBS or thalamotomy for parkinsonian tremor. Some patients with highly asymmetric tremor-dominant PD might be appropriately treated with unilateral instead of bilateral STN DBS.     

Deep brain stimulation and medication for parkinsonian tremor during secondary tasks.

This study examined the efficacy of subthalamic nucleus (STN), deep brain stimulation (DBS), and medication for resting tremor during performance of secondary tasks. Hand tremor was recorded using accelerometry and electromyography (EMG) from 10 patients with Parkinson's disease (PD) and ten matched control subjects. The PD subjects were examined off treatment, on STN DBS, on medication, and on STN DBS plus medication. In the first experiment, tremor was recorded in a quiet condition and during a cognitive task designed to enhance tremor. In the second experiment, tremor was recorded in a quiet condition and during isometric finger flexion (motor task) with the contralateral limb at 5% of the maximal voluntary contraction (MVC) that was designed to suppress tremor. Results showed that: (1) STN DBS and medication reduced tremor during a cognitive task that exacerbated tremor, (2) STN DBS normalized tremor frequency in both the quiet and cognitive task conditions, whereas tremor amplitude was only normalized in the quiet condition, (3) a secondary motor task reduced tremor in a similar manner to STN DBS. These findings demonstrate that STN DBS still suppresses tremor in the presence of a cognitive task. Furthermore, a secondary motor task of the opposite limb suppresses tremor to levels comparable to STN DBS.     

Subthalamic nucleus stimulation in tremor dominant parkinsonian patients with previous thalamic surgery

Before the introduction of high frequency stimulation of the subthalamic nucleus (STN), many disabled tremor dominant parkinsonian patients underwent lesioning or chronic electrical stimulation of the thalamus. We studied the effects of STN stimulation in patients with previous ventral intermediate nucleus (VIM) surgery whose motor state worsened. Fifteen parkinsonian patients were included in this study: nine with unilateral and two with bilateral VIM stimulation, three with unilateral thalamotomy, and one with both unilateral thalamotomy and contralateral VIM stimulation. The clinical evaluation consisted of a formal motor assessment using the Unified Parkinson's Disease Rating Scale (UPDRS) and neuropsychological tests encompassing a 50 point frontal scale, the Mattis Dementia Rating Scale, and the Beck Depression Inventory. The first surgical procedure was performed a mean (SD) of 8 (5) years after the onset of disease. STN implantation was carried out 10 (4) years later, and duration of follow up after beginning STN stimulation was 24 (20) months. The UPDRS motor score, tremor score, difficulties in performance of activities of daily living, and levodopa equivalent daily dose significantly decreased after STN stimulation. Neither axial symptoms nor neuropsychological status significantly worsened after the implantation of the STN electrodes. The parkinsonian motor state is greatly improved by bilateral STN stimulation even in patients with previous thalamic surgery, and STN stimulation is more effective than VIM stimulation in tremor dominant parkinsonian patients.     

The oscillatory activity in the Parkinsonian subthalamic nucleus investigated using the macro-electrodes for deep brain stimulation.

OBJECTIVES: To investigate the oscillatory activity in the Parkinsonian subthalamic nucleus using the macro-electrodes for deep brain stimulation. METHODS: During bilateral deep brain stimulating electrode implantation, spontaneous and evoked field potentials were recorded from the subthalamic nucleus (STN) in two patients with Parkinson's disease (PD) during spontaneous resting tremor, passive manipulation of the wrist, and following electrical stimulation of the contralateral STN. RESULTS: Frequency analysis of the STN field potentials recorded during spontaneous resting tremor showed significant coherence with electromyographic activity in the contralateral arm, suggesting a close involvement of the STN in the generation of resting tremor in PD. The STN responded to passive movement of the contralateral wrist, but not to ipsilateral movement. High frequency (100 Hz) electrical stimulation of the STN induced tremor (4 Hz) in both forearms, and also oscillation of the contralateral STN (4 Hz). In contrast, low frequency (5 Hz) stimulation induced contralateral arrhythmic involuntary movement (3 Hz), but without altering the contralateral STN activity. CONCLUSIONS: We propose that the functional connection between the STN and arm muscles is mainly contralateral, but cross talk may occur between bilateral STN via a frequency-dependent pathway.     

Stimulation of the subthalamic nucleus in a patient with Parkinson disease and essential tremor

BACKGROUND: The preferred surgical target for the treatment of Parkinson disease (PD) is either the internal globus pallidus or the subthalamic nucleus (STN); the target for treatment of essential tremor (ET) is the thalamic subnucleus ventralis intermedius (Vim). Some patients with PD have coexistent ET, and the identification of a single surgical target to treat both parkinsonian motor symptoms and ET would be of practical importance. OBJECTIVE: To describe the use of the STN target in deep brain stimulator (DBS) surgery to treat PD motor symptoms and the action-postural tremor of ET. DESIGN: Case report. PATIENT: A 62-year-old man had a greater than 30-year history of action-postural tremor in both hands, well controlled with beta-blockers for more than 20 years. He developed resting tremor, bradykinesia, and rigidity on his right side that progressed to his left side during the past 10 years. Dopaminergic medication improved his rigidity and bradykinesia, with only mild improvement of his resting tremor and no effect on his action-postural tremor. INTERVENTIONS: Left pallidotomy followed by placement of a left DBS in the Vim and subsequent placement of a right STN DBS. MAIN OUTCOME MEASURES: Control of symptoms of PD and ET. RESULTS: The left pallidotomy controlled the patient's parkinsonian motor symptoms on the right side of his body, but did not affect the action-postural component of his tremor. The symptoms on the left side of the body, including both an action-postural and a resting tremor (as well as the rigidity and bradykinesia), improved after placement of a single right STN DBS. CONCLUSION: Placement of an STN DBS should be considered as the procedure of choice for surgical treatment of patients with a combination of PD and ET.     

Tremor reduction by subthalamic nucleus stimulation and medication in advanced Parkinson’s disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has proved to be effective for tremor in Parkinson’s disease (PD). Most of the recent studies used only clinical data to analyse tremor reduction. The objective of our study was to quantify tremor reduction by STN DBS and antiparkinsonian medication in elderly PD patients using an objective measuring system. Amplitude and frequency of resting tremor and re-emergent resting tremor during postural tasks were analysed using an ultrasound-based measuring system and surface electromyography. In a prospective study design nine patients with advanced PD were examined preoperatively off and on medication, and twice postoperatively during four treatment conditions: off treatment, on STN DBS, on medication, and on STN DBS plus medication. While both STN DBS and medication reduced tremor amplitude, STN DBS alone and the combination of medication and STN DBS were significantly superior to pre- and postoperative medication. STN DBS but not medication increased tremor frequency, and off treatment tremor frequency was significantly reduced postoperatively compared to baseline. These findings demonstrate that STN DBS is highly effective in elderly patients with advanced PD and moderate preoperative tremor reduction by medication. Thus, with regard to the advanced impact on the other parkinsonian symptoms, STN DBS can replace thalamic stimulation in this cohort of patients. Nevertheless, medication was still effective postoperatively and may act synergistically. The significantly superior efficacy of STN DBS on tremor amplitude and its impact on tremor frequency in contrast to medication might be explained by the influence of STN DBS on additional neural circuits independent from dopaminergic neurotransmission. Received in revised form: 27 April 2006     

Ten Hertz thalamus stimulation increases tremor activity in the subthalamic nucleus in a patient with Parkinson's disease

OBJECTIVE: In patients with Parkinson's disease (PD) the effect of thalamic stimulation on tremor pathophysiology remains largely unclear. By recording local field potentials (LFPs) in the subthalamic nucleus (STN) while stimulating the nucleus ventralis intermedius thalami (VIM), information of the stimulation effects should be gained. METHODS: We had the unique opportunity to intraoperatively record LFPs of the STN in a patient with PD while stimulating the VIM. VIM electrodes had been implanted 9 years previously because of tremor. Due to worsening of clinical symptoms an implantation of STN electrodes had become necessary. RESULTS: High frequency stimulation in the VIM lowered the power of the tremor frequency band (4-7Hz) in the STN. In contrast, 10Hz VIM stimulation elevated the power of the tremor frequency band as well as STN-EMG coupling. CONCLUSIONS: The effect of high frequency stimulation may explain the improvement of tremor in patients who are treated with VIM deep brain stimulation. The power elevation during 10Hz stimulation suggests that the pathological cerebral and cerebral-muscular communication in PD is mainly driven at 10Hz. SIGNIFICANCE: The direct cerebral recordings support the view that a 10Hz network is a pathophysiological key mechanism in the generation of motor deficits in PD.     

Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson's disease

Evidente VGH, Premkumar AP, Adler CH, Caviness JN, Driver‐Dunckley E, Lyons MK. Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson’s disease.
Acta Neurol Scand: 2011: 124: 211–214.
© 2010 John Wiley & Sons A/S. Objective – To compare the medication dose reduction between deep brain stimulation (DBS) of the globus pallidus interna (GPi) vs subthalamic nucleus (STN) in matched patients with Parkinson’s disease (PD). Materials and methods – Records of 12 patients with PD who underwent GPi‐DBS at our institution from 2002 to 2008 were matched by pre‐operative PD medication doses and pre‐operative motor Unified Parkinson’s Disease Rating Scale (UPDRS) scores to 12 cases of STN‐DBS. PD medication doses were converted to levodopa equivalent doses (LEDs). Results – GPi and STN groups had similar mean pre‐operative LEDs and motor UPDRS scores. At 6 months post‐DBS, there was no significant difference in percent reduction in LEDs between the GPi (47.95%) and STN (37.47%) groups (P = 0.52). The mean post‐operative ‘medication off/stimulation on’ motor UPDRS scores did not differ significantly between GPi (15.33) and STN (16.25) groups (P = 0.74). The mean percent reduction in motor UPDRS scores was also similar between GPi (58.44%) and STN (58.98%) patients (P = 0.94). Conclusions – We conclude that in disease‐matched patients with PD undergoing DBS, both GPi and STN may result in similar reduction in PD medication doses.     

Combination targeting of subthalamic nucleus and ventral intermediate thalamic nucleus with a single trajectory in deep brain stimulation for tremor-dominant Parkinson’s disease

Deep brain stimulation (DBS) has traditionally been used to target the subthalamic nucleus (STN) or globus pallidus internus (GPi) to treat Parkinson’s disease (PD) and the ventral intermediate thalamic nucleus (VIM) to treat essential tremor (ET). Recent case reports have described targeting both the STN and VIM with a single trajectory and electrode to treat patients with tremor-dominant PD, yet outcome data for this procedure remains sparse. Our objective is to determine the safety and efficacy of combination STN-VIM DBS. We conducted a single-center retrospective case series of all patients who underwent combined STN-VIM DBS. Demographic, perioperative, and outcome data, including Unified Parkinson Disease Rating Scale-III (UPDRS) and tremor scores (OFF-medication), and levodopa equivalent daily dose (LEDD), were collected and analyzed. Nineteen patients underwent this procedure. Patients were 89% male and 11% female, with a mean age of 63.6 years. Mean preoperative UPDRS was 24.1, and LEDD was 811.8. At a mean follow-up of 33.8 months, UPDRS and LEDD decreased by an average of 9.2 (38.2%) and 326.3 (40.2%), respectively. Tremor scores decreased by 4.9 (59.0%), and 58% were able to decrease total medication burden. One patient developed transient left-sided weakness, yielding a complication rate of 5.3%. Combined targeting of STN and VIM thalamus via a single frontal trajectory for tremor-dominant Parkinson’s Disease results in similar UPDRS outcomes to STN DBS and improved control of tremor symptoms. Larger multicenter studies are necessary to validate this as the optimal DBS target for tremor-dominant PD.     

Two‐year follow‐up on the effect of unilateral subthalamic deep brain stimulation in highly asymmetric Parkinson's disease

Although bilateral subthalamic deep brain stimulation (STN DBS) provides greater relief from the symptoms of Parkinson's disease (PD) than unilateral STN DBS, it has been suggested that unilateral STN DBS may be a reasonable treatment option in selected patients, especially those with highly asymmetric PD. In previous studies on the effect of unilateral STN DBS, the asymmetry of PD symptoms was not prominent and the mean follow‐up durations were only 3 to 12 months. In this study, we report our findings in a series of 8 patients with highly asymmetric PD who were treated with unilateral STN DBS and were followed for 24 months. Serial changes in Unified Parkinson's Disease Rating Scale (UPDRS) motor score and subscores in the ipsilateral, contralateral, and axial body parts were analyzed. Unilateral STN DBS improved the UPDRS motor score and the contralateral subscore in the on‐medication state for 5 nonfluctuating patients and in the off‐medication state for 3 fluctuating patients. However, the ipsilateral subscore progressively worsened and reversed asymmetry became difficult to manage, which led to compromised medication and stimulator adjustment. At 24 months, all the patients were considering the second‐side surgery. Our results suggest that bilateral STN DBS should be considered even in highly asymmetric PD. © 2008 Movement Disorder Society     

Bilateral subthalamic nucleus stimulation after bilateral pallidotomies in a patient with advanced Parkinson's disease

A 54-year-old man with advanced Parkinson's disease (PD) presented to our institution in early 2000. He had undergone a right pallidotomy in 1994, a left pallidotomy in 1996, and bilateral subthalamic nucleus (STN) electrode implants in 1999. The patient had cervical myelopathy for which he had undergone neck surgery in 1998. We used the Unified Parkinson's Disease Rating Scale (UPDRS) to evaluate motor performance in four states: combinations of stimulation OFF or ON and medication OFF or ON. There was no significant change in motor UPDRS scores with STN stimulation or with medications. Multiple attempts to optimize stimulation parameters and medication dosages did not result in significant and sustained improvement in activities of daily living or motor performance. To our knowledge, this is the first reported case of bilateral STN stimulation after bilateral pallidotomies. The presence of cervical myelopathy and the limited response to anti-Parkinson medications in this patient underscores the importance of patient selection for functional neurosurgery in PD.     

Thalamic deep brain stimulation: comparison between unilateral and bilateral placement

BACKGROUND: Unilateral thalamic deep brain stimulation (DBS) is accepted as an effective treatment for essential tremor (ET) and the tremor of Parkinson disease (PD). There are, however, relatively little data concerning bilateral thalamic DBS and no thorough comparisons between the 2 methods. METHODS: To assess the relative benefit of a staged second contralateral DBS placement in patients with PD and ET, we compared preoperative baseline assessments with those at 3 months after the initial implantation, and again at 3 months after the second contralateral implantation. The assessments included the Unified Parkinson's Disease Rating Scale for patients with PD (n = 8) and a modified Unified Tremor Rating Assessment for patients with ET (n = 13). The design included open and blinded (unknown activation status) assessments. RESULTS: Overall, after the second implantation, all specific measures assessing tremor contralateral to that side improved in patients with PD and ET, generally without sacrificing those contralateral to the first side implantation. Midline tremors (face and head) improved only after the second side implantation. In patients with ET, functional and subjective scores tended to further improve after the second placement; however, patients with PD had less subjective improvement. Hand tremor scores in patients with ET randomized to "on" stimulation improved from 6.7 +/- 0.9 to 1.3 +/- 1.2 (P<.005). The scores of patients with PD randomized to on stimulation improved from 9.3 +/- 1.0 to 1.0 +/- 0.5. (Data are given as mean +/- SD.) Tremor scores did not change from baseline in those patients randomized to "off" stimulation in either group. Adverse events related to stimulation increased after the second implantation in both groups. CONCLUSIONS: Bilateral thalamic DBS is more effective than unilateral DBS at controlling bilateral appendicular and midline tremors of ET and PD. Despite this, overall functional disability only improved in patients with ET, possibly secondary to more problematic adverse events in patients with PD, especially balance problems. Bilateral DBS should be considered when unilateral DBS does not offer satisfactory benefit, especially in patients with ET.     

The effects of subthalamic nucleus deep brain stimulation on parkinsonian tremor

Deep brain stimulation (DBS) of the ventral intermediate (Vim) nucleus of the thalamus has been the target of choice for patients with disabling essential tremor or medication refractory parkinsonian tremor. Recently there is evidence that the subthalamic nucleus (STN) should be the targets for patients with tremor associated with Parkinson's disease (PD). To assess the effects of STN DBS on parkinsonian tremor, eight consecutive patients with PD and disabling tremor were videotaped using a standardized tremor protocol. Evaluations were performed at least 12 h after last dose of medication with the DBS turned off followed by optimal DBS on state. A rater blinded to DBS status evaluated randomized video segments with the tremor components of the Unified Parkinson Disease Rating Scale (UPDRS) and Tremor Rating Scale (TRS). Compared with DBS off state there were significant improvements in mean UPDRS tremor score 79.4% (p = 0.008), total TRS score 69.9% (p = 0.008) and upper extremity 92.5% (p = 0.008) TRS subscore. Functional improvement was noted with pouring liquids. Our findings provide support that STN DBS is an effective treatment of tremor associated with PD.     

OFF-off rebound dyskinesia in subthalamic nucleus deep brain stimulation of Parkinson's disease.

A 61-year-old man with Parkinson's disease (PD), motor fluctuations, and dyskinesias underwent bilateral implantation of deep brain stimulation (DBS) electrodes in the subthalamic nucleus (STN). One month after surgery, DBS was optimized to bilateral monopolar settings at the most proximal electrode just superior to the STN, which improved motor fluctuations and dyskinesias. At several postoperative evaluations off medications overnight, both stimulators were turned off and within 60 seconds he developed severe dyskinesias. When the stimulators were turned back on, the dyskinesias soon resolved. This article is a first report of a unique pattern of rebound-type dyskinesia that occurred in the off medication state produced by stopping STN DBS.     

Effect of short and long term STN stimulation periods on parkinsonian signs

Currently, no study of subthalamic nucleus (STN) stimulation has compared continuous stimulation with a period of short‐term stimulation, which is frequently employed in the clinic and in research studies. Therefore, this study examined the effects of STN stimulation over 90 min (short) and greater than 3 months (long) on the cardinal signs of Parkinson's disease. The 90 min time period immediately followed a 12 hour withdrawal from both STN stimulation and medication. Ten PD patients who received STN stimulation were studied. Bradykinesia, rigidity, and tremor were evaluated using the UPDRS and motor control measures which included peak velocity (bradykinesia), work (rigidity), and amplitude (tremor). Results showed no difference between 90 min and greater than 3 months of STN stimulation for the UPDRS or motor control measures. This finding confirms that the treatment efficacy that is derived from a relatively short time course of stimulation generalizes to longer time periods of high frequency STN stimulation that patients experience in their daily lives. As such, it is reasonable to evaluate the effect of DBS after 90 min of stimulation in clinical trials and research studies. © 2008 Movement Disorder Society     

Chronic subthalamic nucleus stimulation reduces medication requirements in Parkinson's disease.

OBJECTIVE: To reduce antiparkinsonian medication in parkinsonian patients with bilateral high frequency subthalamic nucleus (STN) stimulation. BACKGROUND: Parkinsonian syndromes are characterized by hyperactivity of the STN. Preliminary data indicate that functional inactivation of the STN may reduce the requirement for dopaminergic therapy in PD. METHODS: Bilateral quadripolar leads were implanted stereotactically in the STN of seven patients with advanced PD (mean age, 57.4 years; mean disease duration, 15.4 years). High-frequency stimulation was applied for 24 hours a day. Following implantation, antiparkinsonian medication was reduced to the minimum possible and stimulation was gradually increased. The patients were evaluated in the practically defined "off" and "on" conditions using the Unified Parkinson's Disease Rating Scale (UPDRS) and the Schwab & England scale. The average follow-up was 16.3+/-7.6 months. A battery of neuropsychological tests was applied before and 9 months after the implant. RESULTS: Parkinsonian features improved in all patients--the greatest change seen in rigidity, then tremor, followed by bradykinesia. Compared with the presurgical condition, off-drug UPDRS motor scores improved by 41.9% on the last visit (p = 0.0002), UPDRS activities of daily living (ADL) scores improved by 52.2% (p = 0.0002), and the Schwab & England scale score improved by 213% (p = 0.0002). The levodopa-equivalent daily dose was reduced by 65%. Night sleep improved in all patients due to increased mobility at night, and in five patients insomnia was resolved. All patients gained weight after surgery and their appetite increased. The mean weight gain at the last follow-up was 13% compared with before surgery. During the last visit, the stimulation amplitude was 2.9+/-0.5 V and the total energy delivered per patient averaged 2.7+/-1.4 W x10(-6). The results of patient self-assessment scales indicated a marked improvement in five patients and a moderate improvement in the other two. The neuropsychological data showed no changes. Side effects were mild and tolerable. In all cases, a tradeoff between the optimal voltage and the severity of side effects made it possible to control parkinsonian signs effectively. The most marked side effects directly related to STN stimulation consisted of ballistic or choreic dyskinesias of the neck and the limbs elicited by contralateral STN stimulation above a given threshold voltage, which varied depending on the individual. CONCLUSIONS: Parkinsonian signs can be controlled by bilateral high-frequency STN stimulation. The procedure is well tolerated. On-state dyskinesias were greatly reduced, probably due to the reduction of total antiparkinsonian medication. Bilateral high-frequency STN stimulation compensated for drug reduction and elicited dyskinesias, which differ from those observed following dopaminergic medication. ADL improved significantly, suggesting that some motor tasks performed during everyday chores, and that are not taken into account in the UPDRS motor score, also improved.     

Unilateral thalamic deep brain stimulation in essential tremor demonstrates long-term ipsilateral effects

IntroductionDeep Brain Stimulation (DBS) of thalamus in essential tremor (ET) is effective for the treatment of contralateral tremors. Bilateral DBS controls tremors on both sides but is associated with increased morbidity and risks. We evaluated if unilateral surgery had ipsilateral benefits on tremors and thus could be a potentially safer alternative to bilateral DBS.MethodsMedication refractory ET patients undergoing unilateral thalamic DBS were included and longitudinally followed. Tremor rating scale was used to record total motor, arm tremor and activities of daily living (ADL) scores at baseline, six months and at last visit (three or more years after surgery). Postoperative scores were recorded with DBS turned OFF and ON.ResultsTwenty-two patients with a mean follow-up 3.4 ± 0.14 years were enrolled. When baseline scores were compared to scores with the DBS turned ON, significant improvements were noted in total tremor (40%), ADL (67%) and arm tremor scores both on the ipsilateral and the contralateral side at six months and at the last visit of follow-up (all p < 0.05). Ipsilateral arm tremor (～56%) improvements were milder compared to the contralateral side (～73%) tremors.ConclusionUnilateral thalamic DBS in ET demonstrates significant long-term benefits for ipsilateral arm tremors and can be offered to higher risk and to select patients.     

A comparison of neuropsychological effects of thalamotomy and thalamic stimulation

OBJECTIVE: The neuropsychological effects of thalamotomy and thalamic stimulation in patients with severe drug-resistant tremor due to PD, essential tremor (ET), or MS were compared in a randomized trial. METHODS: Complete neuropsychological evaluations at baseline and 6 months after surgery were obtained in 62 patients who underwent thalamotomy (n = 32: 21 PD, 6 ET, 5 MS) or thalamic stimulation (n = 30: 19 PD, 7 ET, 4 MS). RESULTS: Six months after thalamotomy, a decline was seen in the scores of the Stroop Color-Word Test, with the exception of the interference score. In the thalamic stimulation group, no significant changes were found on any of the cognitive tests. Age, diagnosis, disease severity, and baseline cognitive status were not correlated to cognitive changes. A difference in score changes between right- and left-sided surgery was found in verbal fluency and Stroop Test scores after both thalamotomy and thalamic stimulation. CONCLUSIONS: Both thalamotomy and thalamic stimulation are associated with a minimal overall risk of cognitive deterioration. Verbal fluency decreased after both left-sided thalamotomy and thalamic stimulation.     

Neurosurgery for Parkinson's disease

Medical therapy for Parkinson's disease (PD) often becomes inadequate over several years. Disability increases despite maximal medical management and many patients develop motor fluctuations and dyskinesia. In addition, medications provide good control of tremor in only 50% of cases. In appropriately selected cases, surgical therapies for PD provide benefit for medically refractory symptoms. Recent advances have provided a greater array of surgical options. Unilateral thalamotomy and thalamic stimulation are considered safe and effective procedures to treat contralateral tremor. Pallidotomy and pallidal stimulation primarily reduce contralateral dyskinesia, with lesser effects on bradykinesia and rigidity. Studies indicate that subthalamic nucleus (STN) stimulation improves "off" period function, decreases "off" time, and lessens dyskinesia. Fetal cell transplantation remains experimental, and studies are underway to evaluate the safety and efficacy of porcine fetal cell and human retinal pigment epithelial cell transplantation. This chapter reviews the history of surgical procedures for PD, describes current procedures, and offers a look into the future of neurosurgical options for PD.     

丘脑底核电刺激治疗帕金森病的临床应用

目的探讨丘脑底核(STN)脑深部电刺激术(DBS)治疗帕金森病(PD)的手术方法和脉冲发生器的程控调节。方法行STN DBS治疗PD61例,其中单侧30例,双侧31例。采用磁共振扫描结合微电极记录技术进行靶点定位。术后用UPDRS运动评分评价刺激效果。结果术后随访6～36个月,平均11.3个月。脉冲发生器开启时,在“关”状态下,UPDRS运动评分改善率5.2%;在“开”状态下,UPDRS运动评分改善率20.7%,未发现任何并发症。结论STN DBS能有效控制PD症状,手术并发症少,术后可调节参数,已成为治疗PD的重要手术方法。